Development of arterial plaque results from oxidation of lipoproteins, particularly low-density lipoproteins. SPECIFIC AIM: The objective of this study is to determine the mechanisms governing the free radical oxidation of lipids and proteins in low-density lipoproteins (LDL). LDL are isolated from fresh human blood and exposed to free redical initiators. Products of LDL oxidation are isolated and the effect of natural and man-made antioxidants are assessed.